1. Field of the Invention
The present invention relates to an alarm setting device, and particularly to an alarm setting device that is capable of adjusting the alarm setting time by rotating in a clockwise as well as a counterclockwise direction of an axle for adjusting the alarm setting wheel.
2. Prior Art
Alarm setting devices which can be operated by reciprocal rotation of the axle for adjusting the alarm setting wheel to adjust the alarm setting time have been known generally. For example, such a type of alarm setting device is proposed in Japanese Laid-Open Patent Application No. 53-11816. That is, in an alarm setting mechanism wherein an hour hand wheel and an alarm setting wheel are disposed coaxially, an engaging portion of the alarm setting wheel is provided with a sloped depression surface and a sloped shoulder to engage a projection of the hour hand wheel. Also, between the alarm setting wheel and the hour hand wheel, an alarm setting cam is disposed. This alarm setting cam can be made to swing back and forth through a predetermined angle. Furthermore, a finger of the alarm setting cam is always positioned on the engaging portion of the alarm setting wheel by an elastic arm that is combined with the alarm setting wheel to form a single body.
Then, when the hour hand wheel rotates clockwise, the protrusion of the hour hand wheel drops into the engaging portion of the alarm intermediate wheel from a position on a finger of the alarm setting cam. Thereafter, when this protrusion rises due to the slope of the alarm setting wheel, the desired alarm setting operation is performed. On the other hand, when the hour hand wheel rotates reversely wherein the protrusion of the hour hand wheel is depressed into the engaging portion of the alarm setting wheel, the vertical surface of the protrusion of the hour hand wheel presses and moves the finger of the alarm setting cam. By doing so, the protrusion rises up the slope of the engaging portion of the alarm intermediate wheel.
However, this alarm setting mechanism requires an extremely complicated structure including installation of an elastic arm in the alarm setting wheel and thereby pushes the cost of manufacturing up. In addition, in such conventional types of alarm setting devices for timepieces, the elastic arm is combined with the alarm setting wheel to form a single unit. Therefore, as a result of use over a long period of time, elastic deformation of the elastic arm occurs which results in a disturbance in the swinging motion of the alarm setting cam. As a result, it occurs that the finger of the alarm setting cam does not reach to the position on the engaging portion of the alarm intermediate wheel upon alarm setting time with the result that the alarm setting precision is lowered.